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The Dharavi Model: Was It Herd Immunity or Just Plain Luck?

The Dharavi Model: Was It Herd Immunity or Just Plain Luck?

Community health volunteers check the temperature of a woman during a check up campaign for COVID-19 at a slum in Mumbai, August 16, 2020. Photo: Reuters/Francis Mascarenhas.

Mumbai: While the 90-feet-road presented a picture of a normal Dharavi, Down To Earth decided to move a bit further north from here. Our fixer, Rajesh Prabhakar, and Dharavi-based volunteer, Arun Kunchikor, insisted we visit areas that rarely attract the attention of either the media or the administration.

We reached Rajiv Gandhi Nagar’s Uttar Seva Sangh Chawl. We went towards its farthest end. It was just a few metres from the main road. However, it took us 15 minutes to cross several narrow by-lanes.

Two persons can’t walk alongside without brushing against each other in these alleys. I held on to the huts on either side to maintain balance as a drain was flowing beneath and the heavy downpour made it more difficult.

At the farthest end and on bank of the Mithi river, we met Radha and Karishma, two women in their late 20s. “Would you believe that we are safe here and we did not contract infection?” they asked me.

They then answered themselves: “No healthcare worker ever reached us. We kept waiting. Are you also here to tell us that the pandemic is over here and Dharavi has become a model, as TV has been telling us?”

“Social-distancing is a term for big city people. We are scared to death every time we go to the community toilet because it is so dirty,” they rued.

We decided to explore more and went to Dharavi’s 10 localities – Rajiv Gandhi Nagar, Koliwada, Vijay Nagar, Kamla Nagar, Naik Nagar, Prem Nagar, Transit Camp, Arjun Nagar, Dharavi Crossroads and Kumbharwarda – to learn about people’s experiences during our six-day visit to Mumbai.

Vaishali Tikre (32) in Koliwada and Vijay Aleppa Kunchikor (43), who lives in block no. 7 of Transit Camp, said a COVID-19 death had happened right in front of their home in April. Until the day we visited – July 19 – no health worker had ever come to their respective areas, they said.

Rupali Veerkar (35) of Vijay Nagar’s block no. 4, and Syed Wasim Ali of Naik Nagar and Shankar Balram of Prem Nagar did not see COVID-19 deaths in their localities but their experiences were the same. Sarawati Kunchikor (27), a resident of Kamla Nagar’s Lal Chawl, proved to be an exception.

Not one of these families had undergone a COVID-19 test.

While all of them had complaints about their areas being ignored, Sunny Mahadeo Gadre, living in Arjun Nagar, presented a picture of acute apathy to someone who was diagnosed positive with the virus.

Also read: Where in India’s COVID-19 Response Is the Moral Compass That Guides Governance?

When 28-year-old Tikre’s mother complained of food-poisoning on April 1, he took her to a private hospital. She was given antibiotics. But his mother’s health deteriorated. He took her to a government facility, Sion Hospital, where doctors informed him about an abnormal drop in her blood pressure. She was admitted.

“But there, we found one female and two male patients on every bed,” recounted Sunny. Fearing infection, he prodded the doctors for a single bed. A doctor replied, “Doosre patient ke off hone ka wait karo (Wait for a patient to die).”

When Sunny’s mother tested positive for COVID-19, she was shifted to a COVID-19 ward. Contrary to the usual practice of not allowing attendants with infected patients, doctors told Sunny to stay and take care of his mother. There were two attendants with every COVID-19-positive patient.

Three days later, he received a call from the Brihanmumbai Municipal Corporation (BMC) asking him to be in his house within 30 minutes and be ready to be taken out to a quarantine centre since he was with his COVID-19-positive mother. This left him puzzled as to who would care for his mother. He, anyway, went home.

Nobody came until that evening, Sunny said, when he got a call from the hospital: “Where are you? Your mother is unconscious and lying on the bed in a pool of urine. You come and clean it,” the nurse said. He rushed. Ultimately, his mother died on April 7.

Sunny’s trauma did not die with the death of his mother. He had to get himself tested. Ideally, this was the duty of the BMC. A day after his mother’s death, he kept running from one hospital to another for a test. But he was refused by all the five hospitals in Dharavi, which included both government and private ones. Finally, on April 9, his estranged father arranged a COVID-19 test for Sunny at a railway hospital.

He tested positive and was self-quarantined in his one room; his wife was sent to her mother’s home during that period. “Nobody came to sanitise the community toilets or ask [after] our well-being. Four families in my area experienced COVID-19 deaths,” Sunny said.

We encountered several such lapses that pointed to one question: How could screening for symptoms of just 40% of the population, aided by a minuscule number of tests (15,000 in a population of 0.8 million), be a successful surveillance strategy?

“The success indicated by news reports about Dharavi gave me an impression that a large number of tests must have been conducted there. I am learning for the first time that just screening, with negligible testing, helped the area,” Ramanan Laxminarayan, founder-director of the Centre for Disease Dynamics, Economics and Policy, at the University of Washington, said.

Jayaprakash Muliyil, a leading epidemiologist who is part of one of the Indian government’s sub-committees on COVID-19, said, “Two factors must have worked. One, whatever screening they did, it helped extract the virus out of the system. Two, herd immunity must have done the trick.”

The Tata Institute of Fundamental Research (TIFR), Mumbai, did a serological survey in four wards of the metropolis to understand the prevalence of the spread in July. Seroprevalence shows the proportion of the sample population that has antibodies.

Also read: How Our Cities Turned the National COVID-19 Crisis From Bad to Worse

“We have released the results of the serosurvey done in F-North, R-North and M-West wards of Mumbai. The seroprevalence in the slum population in these three wards was 57%. The results for the survey done in the G-North ward, under which Dharavi falls, are being finalised. But I can clearly say that the seroprevalence in Dharavi slums is very similar to what we found in the slums of the other three wards,” a source from TIFR said. Thus, this also pointed to herd immunity.

However, if antibodies were found in such high proportion of the population, this also meant that this large chunk of the population was infected at one point of time or another. Such high prevalence of infection was explained by the cramped settings that aided the transmission.

However, a very large proportion of them were asymptomatic infections that were mild and didn’t attract medical attention. But they did not get reflected in numbers too, as they were out of both screening and testing nets.

But why did so many remain mild? “It depends on what magnitude of the virus one is exposed to. If the virus transmission is not severe, there will be more mild cases,” National Institute of Immunology’s Satyajit Rath, said.

Some of the medical practitioners we met in Dharavi, gave a rather simplistic explanation that since people in slums are exposed to so many other infections, an innate immunity might have helped too.

Rath, however, rubbished this idea as an elitist imagination about poor people’s unhygienic living conditions.

“There is absolutely no scientific explanation to back this. Even if a general immunity acquired by being exposed to so many viruses is to work, first, it will not work for infinity. If I have been exposed to pathogens 10 days back and I was cleared of it within three days, then the general immunity will not help me against SARS-CoV-2 today. Secondly, even if it is to work, it just can’t do so in such a huge population on a similar scale.”

The fact remains, however, that more than half the people in Dharavi had antibodies – due to severe or mild infection – and this proved to be an advantage. “The high seroprevalence showed that not only were so many protected against the virus, but such a large population also could not spread the infection further,” T. Jacob John, a retired professor of virology at the Vellore-based Christian Medical College, said.

“Luck might have been on the side of Dharavi. Otherwise, with not-so-high screening numbers and next to negligible testing, it was difficult to achieve this. Also, the BMC did not waste time, which many governments did,” he added.

Some experts, however, warned against jumping the gun. K. Srinath Reddy, president of the Public Health Foundation of India and a member of the India’s National COVID-19 Task Force, said, “Those living in Dharavi, who did not have antibodies, may not carry the risk of being infected only till the time they stay in Dharavi as there is hardly anyone to infect them. This is the principle of herd immunity. But if they move out of Dharavi, as things open, they will be very much at risk of being infected.”

The most important question, nonetheless, remains: Is it too early to declare that Dharavi won the battle? What if a second surge emerges? BMC’s deputy health officer Daksha Shah said it might or might not occur.

The outgoing head of the Union government’s Translational Health Science and Technology Institute, Gagandeep Kang, said: “If somebody from outside Dharavi goes there in a social gathering who is unknowingly infected, a super-spreading event may take place. All those who did not have antibodies, which comprises about half of the population, are at great risk of being infected. Herd immunity will not save them.”

Kang added that Dharavi was a laboratory to study the viral disease in a unique setting. “Nowhere globally, have antibodies been reported in such high proportions of a sample population as in Mumbai’s slums. Indian researchers should just jump into launching studies there as these would solve many unknowns of the virus for the world,” she said.

Also read: What Do the Delhi and Mumbai Sero-Survey Results Tell Us About COVID-19 in India?

The refrain among all experts I spoke to was unanimous: “The jury is out. We should wait for some more time before. At present, new cases are being registered in Dharavi almost every day, though in single digits.”

All of them said the mass screening should have continued as the monsoon might lead to an outbreak of several illnesses, that, in turn, might lower immunity levels of people, making them susceptible to a COVID-19 infection. However, we did not find any screening drive continuing when we were roaming around Dharavi in mid-July.

For Dharavi’s people, now that health-related COVID-19 issues have seemingly ended, their ‘real issues’ that arose due to COVID-19 have now pushed them into an existential crisis. Read the third story to find out why people were desperate that we documented those issues instead of the ‘model’.

This article was originally published by Down To Earth and has been republished here with permission.

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